This project will attempt to establish biochemical responses to pharmacological and electrical stimulation of hippocampal slices. Stimulation of hippocampal slices with cholinergic agonists or electrical impulses applied to the fimbria will be carried out. Schaffer collaterals and many fibers will be studied with regard to their ability to increase cyclic GMP content of the CA-3 region. The intracellular effect of cyclic GMP will also be examined by measuring cGMP dependent protein kinase and protein phosphorylation. This project will thereby extend and better characterize the post synaptic sequence of events that results after stimulation of various pathways and synapses and thereby further our understanding of the events triggered by neurotransmitters as they apply to hippocampal functions.